Another document on that site also confirms my practical experience: Correct collimation of an RC scope must include an analysis of off axis performance.
Link (Read the last sentence in bold)
Correct collimation of an RC scope is not trivial. I know this is not the news many people want to hear, but it's true.
For anyone interested, this is how I do it these days.
Link
If anyone has figured out a better way, by all means, please share!
James